Six years after the end of Sri Lanka’s long and bloody civil war, a “silent” conflict is being waged across the island, with tens of thousands of government troops continuing to occupy the north and east and the army expanding its property developments on land belonging to displaced Tamils, a new report claims.

The study says thousands of Tamils are still internally displaced and without homes and livelihoods, adding that those who have been “resettled” through government schemes have often been moved involuntarily to areas that lack proper infrastructure.

Equally disruptive is the Sri Lankan army’s ongoing occupation of what the government terms “high security zones” in the north and east of the country. The reports estimates that in 2014, there were at least 160,000 almost entirely Sinhalese soldiers stationed in the north. With the area’s population standing at a little more than 1 million people, the occupation means there is one soldier for every six civilians.

One woman, whose husband was arrested by the army in 1990 and has not been seen since, told the report’s authors that she and her family had been forced from their home by the army the same year and were still unable to return.

“Today, my home is still occupied by the army, which pays LKR 300 [$2.25; £1.60] a month for the land,” she said. “I went to the human rights commission … and to the district officer to protest the continued occupation of my home. The army says, ‘If the government asks us to move, we will vacate the lands.’ But there is no legal procedure to obtain my land back.”

Having lived in a camp for internally displaced people and then a village that was destroyed by the 2004 tsunami, the woman now relies on a charity to put a roof over her head.

“I have no hope of my husband returning – I hear there are mass graves of the missing – nor that the government will return my land,” she said. “I hear that the UN is investigating. I want the UN to know and investigate what I have gone through.”

The report argues that the military occupation has long ceased to be about ensuring security.

The army officially runs luxury resorts that have been erected on land seized from now–internally displaced peoples

It says tourists can book holidays at luxury beach resorts by calling numbers at the ministry of defence, adding: “These resorts and businesses are located on lands that were previously home to the local Tamil population, who were displaced by the war. They see no sign of return, despite numerous demands and petitions.”

The study says the recent land grabs fall into an old and familiar pattern that has resulted in the marginalisation of Sri Lanka’s Tamil population through violence, pogroms, repressive laws and a “government-orchestrated colonisation of the northern and eastern parts” of the island, traditionally the Tamils’ homeland.

“The notification … calling out the armed forces to exercise police powers under the pretext of public security does not bode well for a return to civilian administration,” says the report. “Instead, the notification suggests concerns around public security and the inadequacy of the police to deal with the situation.”

“The determination and willingness of the international community to ensure justice for the minorities in Sri Lanka, especially the Tamils, is also an open question,” it says. “One thing is clear: the human rights situation in Sri Lanka will not improve until the culture of impunity is replaced with a culture of responsibility, accountability, and fulfilment of full rights of the Tamil community and all other minorities in the country.”

The Sri Lanka High Commission in London rejected several of the report’s assertions, saying the Oakland Institute had overestimated both the number of troops in the northern province and the extent of the military’s property development programme.

It said the number of soldiers deployed in the north was “much less” than 160,000, adding that troops were deployed in different provinces of Sri Lanka according to local security assessments.

The high commission went on: “The reference to the army being engaged in ‘large- scale’ property development, construction projects and business ventures is an exaggeration. However, it may be noted that the new government has pledged to ensure that the military does not engage in civilian areas such as commercial activities – which was permitted by the previous government – and steps are being taken in this regard.”

As a first step, it said, 1,000 acres of land in the Palali high-security zone in the far north of the island were released in March from the control of the army and air force to allow the resettlement of families displaced by the conflict. Similar releases were under way elsewhere in Sir Lanka, it added.

The high commission said that while the armed forces had operated some “welfare shops” in resettlement areas where there was no commercial activity, the shops had now been closed.

On the president’s decision to extend policing powers to the military, it said: “The public security ordinance which confers police powers to armed forces had been in place for many decades … President Maithripala Sirisena only extended it.”